A Frontier Airlines jet seconds from landing at Denver International Airport on Friday came within 50 feet of hitting a small cargo aircraft that had inadvertently entered the runway, the National Transportation Safety Board said.
Pilots of the Frontier A-319 saw the Swearingen Metroliner, Key Lime Air Flight 4216, on the runway as they were about to land and they “immediately executed a missed approach” – aborting the landing.
The incident occurred around 7:28 a.m.
An automated warning called the Airport Movement Area Safety System, or AMASS, alerted air-traffic controllers in DIA’s tower to the looming collision, and controllers told the Frontier crew to pull up and go around for another landing, officials said.
The Key Lime cargo plane apparently took a wrong turn, mistaking runway 35 Left for a taxiway. Key Lime is a charter carrier based at Centennial Airport.
Planes exiting DIA’s cargo ramp most likely would have been directed by controllers to turn left on a taxiway just east of the cargo area to proceed to a takeoff runway. If a crew missed that left turn, the next left would be onto runway 35 Left.
Late Friday, NTSB and Federal Aviation Administration officials still were looking into circumstances of the near collision.
Snow was falling with one- half mile visibility and a ceiling of 600 feet overcast at the time of the incident, NTSB said, but it hasn’t been determined if weather was a factor.
The Frontier plane, Flight 297, from St. Louis, had 45 passengers and five crew members aboard. It landed uneventfully after the missed approach, said Frontier spokesman Joe Hodas.
AMASS works by blending data from a ground radar system that conducts surveillance of planes and other vehicles on the airfield with other data on airborne planes to predict a possible conflict.
Both visual and audible alerts are triggered in the tower by AMASS and controllers must give an immediate order for the incoming plane to abort the landing, according to officials familiar with the system.
“The bottom line is that the system worked,” said FAA spokesman Allen Kenitzer.
Staff writer Jeffrey Leib can be reached at 303-954-1645 or jleib@denverpost.com.
